U.S. Pat. No. 3,815,768 issued in the name of W. M. Goodwin discloses a trailer having side rails that can be mechanically shifted apart to define a circumscribed space wider than a standard freight container or panel-type load. The shift mechanism described in the patent causes the rails to take divergent positions for obtaining adequate clearance relative to the load. The present invention is directed to a trailer that is in some respects similar to the trailer described in U.S. Pat. No. 3,815,768. However the rail-shifting mechanism in our trailer is designed to maintain the rails parallel to one another before and after the shifting operation. This is advantageous in that the trailer can be moved to or from a position straddling a freight container with a minimum amount of back-and-forth maneuvering; the trailer can thereby be steered into relatively close quarters between adjacent containers.
The trailer of this invention is provided with self-contained lift mechanisms that alternately raise and lower a container between ground level and a level above the plane of the rails without tipping or tilting the container. Thus the container is not dragged or skidded along the ground surface so as to possibly damage the container and/or its contents during the lifting or lowering operation.